1. Field of the Invention
The present invention generally relates to telecommunication systems, and more particularly to systems, methods, and computer program products for providing a manual ring-down communication line using the Session Initiation Protocol (“SIP”).
2. Description of the Related Art
A manual ring-down (“MRD”) private line is a communication line commonly used for two parties to maintain a continuous full-duplex communication channel with each other. A typical MRD private line communication device provides a user with the ability to manually signal the communication device on the other side of the line. Upon receiving the signal, the signaled communication device notifies its user audibly and/or visually that the user on the other end of the line wishes to communicate.
MRD private lines date back to a time period when telephones were purely analog devices, and the MRD private line was implemented using a physical copper wire connecting the two communication devices. Because the MRD private line typically was implemented using a fixed physical connection, a dedicated communication path was created through which users could communicate with each other at any time by, for example, picking up a telephone handset and keying a signaling button An alternative to a MRD private line communication device is an automatic ring-down (ARD) private line communication device, which enables its user to automatically signal the communication device on the other side of the line by, for example, merely picking up a telephone handset.
Typical users of manual and automatic ring-down private lines make large volumes of calls from and to fixed locations and require continuous and uninterrupted lines of communication between those locations. Examples of such users are trading floor environments, financial firms, emergency services, and the like. Audio communication in trading floor environments is typically achieved utilizing specialized hardware and software turret switching systems. A turret switching system is a specialized telephony switching system that allows a relatively small number of users to access a large number of external lines and provides enhanced communication features such as hoot-n-holler, push-to-talk, intercom, video and large-scale conferencing.
Users interface with a turret switching system through a trading turret device, which can be implemented in dedicated hardware (sometimes referred to as a “hard” turret) or in a general-purpose computer (sometimes referred to as a “soft” turret). A hard turret is a phone-like desktop device with multiple handsets, external microphones, speakers and buttons. A soft turret is a software application that runs on a trader's desktop personal computer (“PC”) or on a mobile computer such as a Personal Digital Assistant (“PDA”). A soft turret application may be controlled using the native control interface that the computer provides such as a touch screen, stylus, click wheel, or mouse and keyboard. In addition to rendering a graphical image of the turret on the PC screen, the soft turret application may also provide voice, instant messaging and presence features.
With the advent of Voice over Internet Protocol (“VoIP”), users have begun to communicate over Internet Protocol (“IP”) networks, for example, using telephones implemented in dedicated hardware, or telephones implemented on general purpose computer, which are sometimes referred to as hard telephones and soft telephones, respectively. Supporting MRD functionality in the IP realm, however, necessarily requires customizations to provide, for example, the same persistent connections and signaling.